1. Technical Field
The present invention relates to the field of electronic circuits and more particularly to a mechanical Microsystem comprising a bending beam and a process for manufacturing the same.
2. Description of the Art
Micro Electro Mechanical Systems (M.E.M.S.) have shown for several years a significant development because of their ability to integrate within a single microelectronic circuit a dual electrical and mechanical function.
Different MEMS systems are already known in the art, and particularly microsystems fitted with a bending beam allowing easy manufacturing.
U.S. patent application Ser. No. 11/388,213, which was filed by the Assignee of the present application under priority of FR0502942 filed on Mar. 24, 2005, discloses an example of a micro system comprising a flexible beam, located above one electrode being electromechanically coupled with the beam.
FIG. 1 is a perspective view of such a flexible beam microsystem comprising one substrate 100 having an electrode with an overhanging flexible beam 140 extending along an axis O-y, and which is affixed at its two ends by two anchors 150 located on substrate 100. The flexible beam constitutes a first electrode overhanging above one conductive element 160 located on the substrate and forming a second electrode with which the flexible beam is likely to electrostatically interact.
FIG. 2 illustrates the overhanging beam as it stands without any interaction while FIG. 3 shows the same beam when bent and distorted.
One can thus achieve a set of two electrodes, respectively inferior and superior, the superior electrode forming a resonator with a high quality factor.
Generally speaking, it is desirable to provide different resonance frequencies in one single micro system which comprises a flexible beam, in order to extend the possibilities of use of the MEMS system for the realization of resonators.
In addition, it is desirable to provide an additional micro system which comprises a flexible beam which can be magnetically actuated in a new way.
The following documents are representative of the state of the art in this technical field:
“Resonator-Based Magnetic Field Sensors” by Z. Kadar, A. Bossche, P. M. Sarro, J. R. Mollinger, “Magnetic-Field Measurements Using an Integrated Resonant Magnetic-Field Sensor”, Sensors and Actuators A, 70, pp 225-232, 1998.
“Electromechanical Resonances of SiC and AIN Beams Under Ambient Conditions” by Bruechner K; Forster Ch., Tonisch K., Cimalla V., Ambacher O., Stephan R., Blau K., Hein M. A.